More specifically, the invention relates to the field of blades with variable angle of attack in a rotating housing of an aircraft propeller, or other applications.
FR 2,862,609 describes an example of such a product where the blade is assembled in a housing (called a “hub” in that document) by one of its ends, called the blade root. The root is mounted so as to pivot about an axis substantially perpendicular to and intersecting with the rotor axis in a chamber of the housing. This pivoting, driven by a device (not shown) coupled to an extension of a cap closing off the root, allows adjusting the angle of attack of the blade.
The chamber comprises a stepped side wall, rotationally symmetrical about a radial axis of the propeller which, after installation of the blade, is substantially coincident with the axis of the blade. An inner side of the chamber opens toward the center of the propeller and an outer side opens toward the blade (in that document, and in that context, the terms “inner side and outer side” refer to the location along the radial axis of the propeller).
First and second rows of angular contact rolling elements are mounted between a skirt surrounding the root, and a respective cup and outer ring mounted on the side wall, in a conventional “O” assembly.
The rolling elements, arranged near the outer and inner sides respectively, are tapered rollers and angular contact ball bearings respectively. Each roller has its wide base facing outward.
The cup and the outer ring are supported on the wall by means of plastic protective parts. The outer ring on the inner side is supported on a first shoulder of the hub, preventing it from axial outward movement (in that document, in that context, the terms “inward” and “outward” are used in the conventional manner to describe a bearing, designating the radial location relative to an axis of the bearing).
Inner races for the rollers and ball bearings are respectively formed in the protective skirt.
When the propeller rotates, the blade undergoes two actions:                an axial or centrifugal force for the blade and the rolling bearing that is a function of its speed and mass,        a bending moment at the blade root due to radial force on the blade resulting from the interaction between the blade and the air it is moving.        
To withstand these actions effectively, the rolling bearings are preloaded, in other words a compression of their rolling elements between their races is created and maintained.
While this implementation is entirely satisfactory, there is always a search for ways to improve the performance of these products, maximizing the forces they can withstand while minimizing their footprint.
These research efforts have led to entirely redesigning the product architecture of rolling bearings for blade roots.
In particular, these research efforts have led to an interest in improving the bearing lubrication.
Improving the lubrication of such a bearing is a challenge because, during operation, the lubricant is subjected to centrifugal force. This results in the possibility of lubricant leakage, which may cause damage to a bearing intended to operate with a given amount of lubricant, and/or to the engine due to an excessive imbalance interfering with its operation.